def charge_start(cities, route):
'''
reroute starting point optimally
'''
Nc = cities.shape[0]
new_route = [np.zeros(Nc, dtype=int),
np.zeros(Nc, dtype=int)]
for ir in range(2):
max_ind = -1
max_dist = 0.0
for ic in xrange(Nc-1):
dist = city_dist(cities, route[ir][ic], route[ir][ic+1])
if (dist > max_dist):
max_dist = dist
max_ind = ic
print route[ir][max_ind], route[ir][max_ind+1]
count = 0
for ic in xrange(max_ind+1,Nc):
new_route[ir][count] = route[ir][ic]
count += 1
for ic in xrange(max_ind+1):
new_route[ir][count] = route[ir][ic]
count += 1
return new_route
def opt3(cities, route, look_ahead=9999999, checkpoint=50, name='test'):
Nc = cities.shape[0]
assert(Nc > 0)
# don't want to modify input route...
route = [route[0].copy(),
route[1].copy()]
# fill edges (defined in NN above) and compute distance
# for input route
edges = [-np.ones([Nc,2], dtype=int),
-np.ones([Nc,2], dtype=int)]
dist = np.array([0.0, 0.0])
for ir in range(2):
edges[ir][route[ir][0], 0] = 999999
edges[ir][route[ir][Nc-1], 1] = 999999
for ic in xrange(Nc-1):
dist[ir] += city_dist(cities, route[ir][ic], route[ir][ic+1])
edges[ir][route[ir][ic], 1] = route[ir][ic+1]
edges[ir][route[ir][ic+1], 0] = route[ir][ic]
# route we're currently optimizing is stored in ir
# (always trying to push down maximum distance)
if (dist[0] > dist[1]):
ir = 0
else:
ir = 1
iter = 0
while (1):
# pick three random cities
ic = np.zeros(3, dtype=int)
ic[0] = np.random.randint(low=0, high=Nc-3)
ic[1] = np.random.randint(low=ic[0]+1, high=np.min([ic[0]+look_ahead, Nc-2]))
ic[2] = np.random.randint(low=ic[1]+1, high=np.min([ic[1]+look_ahead, Nc-1]))
#ic = np.array([137293, 137367, 137369])
rr = route[ir]
found = False
dist_old = city_dist(cities, rr[ic[0]], rr[ic[0]+1]) +\
city_dist(cities, rr[ic[1]], rr[ic[1]+1]) +\
city_dist(cities, rr[ic[2]], rr[ic[2]+1])
dist_new = city_dist(cities, rr[ic[0]], rr[ic[1]+1]) +\
city_dist(cities, rr[ic[2]], rr[ic[0]+1]) +\
city_dist(cities, rr[ic[1]], rr[ic[2]+1])
if (dist_new < dist_old):
if ((edges[(ir+1)%2][rr[ic[0]], 0] != rr[ic[1]+1]) &
(edges[(ir+1)%2][rr[ic[0]], 1] != rr[ic[1]+1]) &
(edges[(ir+1)%2][rr[ic[2]], 0] != rr[ic[0]+1]) &
(edges[(ir+1)%2][rr[ic[2]], 1] != rr[ic[0]+1]) &
(edges[(ir+1)%2][rr[ic[1]], 0] != rr[ic[2]+1]) &
(edges[(ir+1)%2][rr[ic[1]], 1] != rr[ic[2]+1]) ):
print 0
route_new = rr.copy();
# rearrange route
count = ic[0]+1
for ii in xrange(ic[1]+1, ic[2]+1):
route_new[count] = rr[ii]
count += 1
for ii in xrange(ic[0]+1, ic[1]+1):
route_new[count] = rr[ii]
count += 1
for ii in xrange(ic[2]+1, ic[0]+1):
route_new[count] = rr[ii]
count += 1
route[ir] = route_new
dist[ir] += (dist_new - dist_old)
found = True
if (found != True):
dist_new = city_dist(cities, rr[ic[0]], rr[ic[1]+1]) +\
city_dist(cities, rr[ic[2]], rr[ic[1]]) +\
city_dist(cities, rr[ic[0]+1], rr[ic[2]+1])
if (dist_new < dist_old):
if ((edges[(ir+1)%2][rr[ic[0]], 0] != rr[ic[1]+1]) &
(edges[(ir+1)%2][rr[ic[0]], 1] != rr[ic[1]+1]) &
(edges[(ir+1)%2][rr[ic[2]], 0] != rr[ic[1]]) &
(edges[(ir+1)%2][rr[ic[2]], 1] != rr[ic[1]]) &
(edges[(ir+1)%2][rr[ic[0]+1], 0] != rr[ic[2]+1]) &
(edges[(ir+1)%2][rr[ic[0]+1], 1] != rr[ic[2]+1]) ):
print 1
route_new = rr.copy();
count = ic[0]+1
for ii in xrange(ic[1]+1, ic[2]+1):
route_new[count] = rr[ii]
count += 1
for ii in xrange(ic[1], ic[0], -1):
route_new[count] = rr[ii]
count += 1
for ii in xrange(ic[2]+1, ic[0]+1):
route_new[count] = rr[ii]
count += 1
route[ir] = route_new
dist[ir] += (dist_new - dist_old)
found = True
if (found != True):
dist_new = city_dist(cities, rr[ic[0]], rr[ic[2]]) +\
city_dist(cities, rr[ic[1]+1], rr[ic[0]+1]) +\
city_dist(cities, rr[ic[1]], rr[ic[2]+1])
if (dist_new < dist_old):
if ((edges[(ir+1)%2][rr[ic[0]], 0] != rr[ic[2]]) &
(edges[(ir+1)%2][rr[ic[0]], 1] != rr[ic[2]]) &
(edges[(ir+1)%2][rr[ic[1]+1], 0] != rr[ic[0]+1]) &
(edges[(ir+1)%2][rr[ic[1]+1], 1] != rr[ic[0]+1]) &
(edges[(ir+1)%2][rr[ic[1]], 0] != rr[ic[2]+1]) &
(edges[(ir+1)%2][rr[ic[1]], 1] != rr[ic[2]+1]) ):
print 2
route_new = rr.copy();
count = ic[0]+1
for ii in xrange(ic[2], ic[1], -1):
route_new[count] = rr[ii]
count += 1
for ii in xrange(ic[0]+1, ic[1]+1):
route_new[count] = rr[ii]
count += 1
for ii in xrange(ic[2]+1, ic[0]+1):
route_new[count] = rr[ii]
count += 1
route[ir] = route_new
dist[ir] += (dist_new - dist_old)
found = True
if (found != True):
dist_new = city_dist(cities, rr[ic[0]], rr[ic[1]]) +\
city_dist(cities, rr[ic[0]+1], rr[ic[2]]) +\
city_dist(cities, rr[ic[1]+1], rr[ic[2]+1])
if (dist_new < dist_old):
if ((edges[(ir+1)%2][rr[ic[0]], 0] != rr[ic[1]]) &
(edges[(ir+1)%2][rr[ic[0]], 1] != rr[ic[1]]) &
(edges[(ir+1)%2][rr[ic[0]+1], 0] != rr[ic[2]]) &
(edges[(ir+1)%2][rr[ic[0]+1], 1] != rr[ic[2]]) &
(edges[(ir+1)%2][rr[ic[1]+1], 0] != rr[ic[2]+1]) &
(edges[(ir+1)%2][rr[ic[1]+1], 1] != rr[ic[2]+1]) ):
print 3
route_new = rr.copy();
count = ic[0]+1
for ii in xrange(ic[1], ic[0], -1):
route_new[count] = rr[ii]
count += 1
for ii in xrange(ic[2], ic[1], -1):
route_new[count] = rr[ii]
count += 1
for ii in xrange(ic[2]+1, ic[0]+1):
route_new[count] = rr[ii]
count += 1
route[ir] = route_new
dist[ir] += (dist_new - dist_old)
found = True
if (found == True):
# rebuild edges
edges[ir][route[ir][0], 0] = 999999
edges[ir][route[ir][Nc-1], 1] = 999999
for ic in xrange(Nc-1):
edges[ir][route[ir][ic], 1] = route[ir][ic+1]
edges[ir][route[ir][ic+1], 0] = route[ir][ic]
iter += 1
score = int(np.max(dist))
print score
if (iter%checkpoint == 0):
# when we checkpoint make sure tours are disjoint and valid
print score, calc_score(cities, route)
#assert(score == calc_score(cities, route))
io.write_route(route, name + '_' + str(score))
# switch to other route if it's longer
if (dist[ir] < dist[(ir+1)%2]):
ir = (ir+1)%2
return route
def NN(cities, start=np.array([0,0])):
'''
Nearest neighbor algorithm
Input are indicies of starting cities
Routes are built incrementally in a greedy fashion, cycling
from one route to another
gives solutions in the 7.9M range
'''
Nc = cities.shape[0]
assert(Nc > 0)
assert((start[0] < Nc) & (start[1] < Nc) &
(start[0] >= 0) & (start[1] >= 0))
myroute = [np.zeros(Nc, dtype=int),
np.zeros(Nc, dtype=int)]
myroute[0][0] = start[0]
myroute[1][0] = start[1]
'''
the edges array keeps track of edges incident
to a city for each route
for example, if city 10 is incident to cities
97 and 436 in route 0,
edges[0][10,0] = 97
edges[0][10,1] = 436
because it is a tour, each city will have at
most 2 edges incident to it
a -1 indicates no edge
'''
edges = [-np.ones([Nc,2], dtype=int),
-np.ones([Nc,2], dtype=int)]
# starting points get dummy edges since we don't
# need to end up here
edges[0][myroute[0][0], 0] = 999999
edges[1][myroute[1][0], 0] = 999999
# keep track of distance as we go...
dist = np.array([0.0, 0.0])
# build kdtree once for cities
tree = cKDTree(cities)
for ic in xrange(Nc-1):
for ir in range(2):
thiscity = myroute[ir][ic]
# make sure this city has degree exactly equal to 1
assert(edges[ir][thiscity, 0] >= 0)
assert(edges[ir][thiscity, 1] == -1)
# start looking at the nearest 10 neighbors,
# increasing this number until a valid city is found
# to continue the tour
knbrs = 10
nextcity = -1
while(nextcity == -1):
nbrs_dist, nbrs = tree.query(cities[thiscity], knbrs)
for nbr in nbrs:
# it's possible that there are no valid cities left,
# right at the end - rare, but has happened
# i.e. the last edge is already used by the other tour
if (nbr == Nc):
print "failed to find next city"
return None, 99999999999
# check if we've already been here...
if (edges[ir][nbr,0] == -1):
# eliminate edges in other route...
if ((edges[(ir+1)%2][thiscity, 0] != nbr) &
(edges[(ir+1)%2][thiscity, 1] != nbr)):
nextcity = nbr
break
# we didn't find a valid city, so increase number of neighbors...
knbrs *= 2
# add next city to route and add distance
myroute[ir][ic+1] = nextcity
dist[ir] += city_dist(cities, thiscity, nextcity)
# fill in edges array
edges[ir][thiscity, 1] = nextcity
edges[ir][nextcity, 0] = thiscity
score = int(np.max(dist))
return myroute, score
def opt2(cities, route, look_ahead=9999999, checkpoint=50, name='test'):
'''
opt-2 takes a route and shortens it by taking
two edges and un-bowties them like so:
* * *-----*
\ /
\ /
/\ ==>
/ \
* * *-----*
checkpoint is number of edges un-bowtied before writing out
the route as name_<dist>.csv
look_ahead is an attempt to make it more efficient - for a given edge,
will only look for edges to perform 2-opt a specified number ahead in route
'''
Nc = cities.shape[0]
assert(Nc > 0)
# don't want to modify input route...
route = [route[0].copy(),
route[1].copy()]
# fill edges (defined in NN above) and compute distance
# for input route
edges = [-np.ones([Nc,2], dtype=int),
-np.ones([Nc,2], dtype=int)]
dist = np.array([0.0, 0.0])
for ir in range(2):
edges[ir][route[ir][0], 0] = 999999
edges[ir][route[ir][Nc-1], 1] = 999999
for ic in xrange(Nc-1):
dist[ir] += city_dist(cities, route[ir][ic], route[ir][ic+1])
edges[ir][route[ir][ic], 1] = route[ir][ic+1]
edges[ir][route[ir][ic+1], 0] = route[ir][ic]
# route we're currently optimizing is stored in ir
# (always trying to push down maximum distance)
if (dist[0] > dist[1]):
ir = 0
else:
ir = 1
iter = 0
while (1):
# pick two random cities
ic0 = np.random.randint(low=0, high=Nc-2)
ic1 = np.random.randint(low=ic0+1, high=np.min([ic0+look_ahead, Nc-1]))
# just an alias to make things shorter...
rr = route[ir]
dist_old = city_dist(cities, rr[ic0], rr[ic0+1]) +\
city_dist(cities, rr[ic1], rr[ic1+1])
dist_new = city_dist(cities, rr[ic0], rr[ic1]) +\
city_dist(cities, rr[ic0+1], rr[ic1+1])
if (dist_new < dist_old):
# check if un-bowtieing conflicts with other tour...
if ((edges[(ir+1)%2][rr[ic0], 0] != rr[ic1]) &
(edges[(ir+1)%2][rr[ic0], 1] != rr[ic1]) &
(edges[(ir+1)%2][rr[ic0+1], 0] != rr[ic1+1]) &
(edges[(ir+1)%2][rr[ic0+1], 1] != rr[ic1+1])):
route_new = rr.copy();
# rearrange route and update edges
count = ic0+1
edges[ir][rr[ic0], 1] = rr[ic1]
edges[ir][rr[ic1], 0] = rr[ic0]
for ii in xrange(ic1, ic0, -1):
route_new[count] = rr[ii]
edges[ir][rr[ii], 1] = rr[ii-1]
if (ii != ic0+1):
edges[ir][rr[ii-1], 0] = rr[ii]
count += 1
edges[ir][rr[ic1+1], 0] = rr[ic0+1]
edges[ir][rr[ic0+1], 1] = rr[ic1+1]
route[ir] = route_new
dist[ir] += (dist_new - dist_old)
iter += 1
score = int(np.max(dist))
print score
if (iter%checkpoint == 0):
# when we checkpoint make sure tours are disjoint and valid
print score, calc_score(cities, route)
#assert(score == calc_score(cities, route))
io.write_route(route, name + '_' + str(score))
# switch to other route if it's longer
if (dist[ir] < dist[(ir+1)%2]):
ir = (ir+1)%2
return route